Determining mechanical properties via ultrasound-induced resonance

Abstract

A device for estimating a mechanical property of a sample is disclosed herein. The device may include a chamber configured to hold the sample; a transmitter configured to transmit a plurality of waveforms, including at least one forcing waveform; and a transducer assembly operatively connected to the transmitter and configured to transform the transmit waveforms into ultrasound waveforms. The transducer assembly can also transmit and receive ultrasound waveforms into and out of the chamber, as well as transform at least two received ultrasound waveforms into received electrical waveforms. The device also includes a data processor that can receive the received electrical waveforms; estimate a difference in the received electrical waveforms that results at least partially from movement of the sample; and estimate a mechanical property of the sample by comparing at least one feature of the estimated difference to at least one predicted feature, wherein the at least one predicted feature is based on a model of an effect of the chamber wall. Finally, the device can also include a controller configured to control the timing of the ultrasound transmitter and data processor.

What is claimed is: 
     
       1. A device for estimating a mechanical property of a sample, comprising:
 a chamber configured to hold the sample; 
 a transmitter configured to transmit a plurality of waveforms, including at least one forcing waveform; 
 a transducer assembly operatively connected to the transmitter and configured to transform the transmit waveforms into ultrasound waveforms, the transducer assembly further configured to transmit and receive ultrasound waveforms into and out of the chamber, and the transducer assembly further configured to transform at least two received ultrasound waveforms into received electrical waveforms; 
 a data processor configured to:
 receive the received electrical waveforms; 
 estimate a difference in the received electrical waveforms that results at least partially from movement of the sample; and 
 estimate a mechanical property of the sample by comparing at least one feature of the estimated difference to at least one predicted feature, wherein the at least one predicted feature is based on a model of an effect of the chamber wall; and 
 
 a controller configured to control the timing of the ultrasound transmitter and data processor. 
 
     
     
       2. The device of  claim 1 , wherein the at least one predicted feature is based on a model of an aspect of the induced movement that is caused at least in part by a boundary effect of the chamber wall. 
     
     
       3. The device of  claim 2 , wherein the mechanical property is an indication of whether or not the chamber wall exhibits an effect on induced displacements. 
     
     
       4. The device of  claim 1 , wherein the at least one predicted feature is based on a model of an aspect of the induced movement that is caused at least in part by resonance within the chamber. 
     
     
       5. The device of  claim 4 , wherein the mechanical property is an indication of whether or not the sample can support mechanical resonance. 
     
     
       6. The device of  claim 4 , wherein the data processor is further configured to calculate a parameter indicating the strength of resonance and omit measurements with a strength of resonance falling below a predetermined threshold. 
     
     
       7. The device of  claim 1 , wherein the at least one predicted feature is based on a model of an aspect of the induced movement that is caused at least in part by reflection of an induced shear wave from the chamber wall. 
     
     
       8. The device of  claim 7 , wherein the mechanical property is an indication of whether or not the sample can support shear wave propagation. 
     
     
       9. The device of  claim 1 , wherein the at least one predicted feature is based on an analytical model. 
     
     
       10. The device of  claim 4 , wherein the at least one predicted feature comprises the period of resonance of the chamber. 
     
     
       11. The device of  claim 1 , wherein the at least one predicted feature is based on a computational model. 
     
     
       12. The device of  claim 1 , wherein the predicted features comprises a table of reference features based on the model. 
     
     
       13. The device of  claim 1 , wherein the data processor is further configured to calculate a correlation value between features of the estimated displacement and features that are based on a model, and omit data falling below a predetermined correlation threshold. 
     
     
       14. The device of  claim 1 , wherein the mechanical property is the shear modulus of the sample. 
     
     
       15. The device of  claim 1 , wherein the transducer assembly comprises a transducer used for both transmitting and receiving. 
     
     
       16. The device of  claim 1 , wherein the transducer assembly comprises a first transducer dedicated to transmitting ultrasound waveforms and a second transducer dedicated to receiving ultrasound waveforms. 
     
     
       17. The device of  claim 1 , wherein the transducer assembly comprises a transducer dedicated to transmitting forcing waveforms and a separate transducer dedicated to transmitting and receiving ultrasound waveforms associated with sensing. 
     
     
       18. The device of  claim 1 , wherein the data processor estimates the mechanical property based on an ensemble of sensing waveforms, the ensemble comprising at least 16 sensing waveforms. 
     
     
       19. The device of  claim 1 , wherein the data processor estimates differences in waveforms received from a plurality of forcing waveforms. 
     
     
       20. The device of  claim 1 , wherein the data processor comprises a received waveform digitizer. 
     
     
       21. The device of  claim 1 , wherein the sample is a blood clot. 
     
     
       22. The device of  claim 1 , wherein the data processor assumes a constant viscosity value for the sample. 
     
     
       23. The device of  claim 1 , wherein the interior surface of the chamber is formed or treated so as to promote adhesion of a forming blood clot. 
     
     
       24. The device of  claim 1 , further comprising a thermal control element in thermal communication with said chamber. 
     
     
       25. The device of  claim 1 , further comprising a focusing unit interposed between the transducer and chamber and configured to focus ultrasound waves transmitted into and received from said chamber. 
     
     
       26. The device of  claim 1 , wherein the chamber is separable from the transducer. 
     
     
       27. The device of  claim 26 , further comprising an ultrasonic couplant interposed between said transducer and said chamber so as to facilitate ultrasound propagation between said transducer and said chamber. 
     
     
       28. The device of  claim 27 , further comprising a clamping element configured to compress said ultrasonic couplant. 
     
     
       29. The device of  claim 27 , further comprising:
 a transducer alignment feature associated with said transducer; and 
 a chamber alignment feature associated with said chamber, 
 wherein said transducer alignment feature and said chamber alignment feature fit together to align said transducer with said chamber. 
 
     
     
       30. A device for characterizing a mechanical property of a sample, comprising:
 a resonant chamber configured to hold the sample; 
 a transmitter configured to transmit a plurality of waveforms, including at least one forcing waveform; 
 a transducer assembly operatively connected to the transmitter and configured to transform the transmit waveforms into ultrasound waveforms, the transducer assembly further configured to transmit and receive ultrasound waveforms into and out of the chamber, and the transducer assembly further configured to transform at least two received ultrasound waveforms into received electrical waveforms; 
 a data processor configured to:
 receive the received electrical waveforms; 
 estimate a difference in the received waveforms that results at least partially from resonance of the sample; and 
 characterize a mechanical property of the sample from at least one feature of the estimated difference; and 
 
 a controller configured to control the timing of the ultrasound transmitter and data processor.